The present invention relates to a refrigerator which uses ammonia as the refrigerant in order to cope with environmental problems such as ozone layer destruction, global warming, or increase of carbon dioxide, and it is particularly suitable for a refrigerator such as a showcase, a freezer, an automatic vending machine, a cooling storage unit and an ice making machine, and for an extremely low temperature refrigerator or the like.
In case of a compressor of the refrigerating cycle using ammonia as the refrigerant, an open type where a compressor and a motor are connected through a shaft is employed, or a stator of the motor is separated from a rotor by a wall called a can, so that contact between the ammonia refrigerant and the winding of the stator may be prevented.
The open type compressor, as it is directly connected to the motor by the connecting device outside the compressor, is large-sized as a unit, and a work of centering at the installation site is necessary. Furthermore, since a shaft seal unit is required on the compressor side, there has been a fear of leakage of the refrigerant and refrigerator oil from seal portions of the shaft seal unit, and it has also been necessary to attain improvement from the viewpoint of safety.
On the other hand, in case of using the can, the structure is complex, and further, the efficiency is lowered. In view of this, it has been known that a closed type compressor is employed and the winding of a stator is coated with aluminum resistant to ammonia as disclosed by JP-A-10-141226, and that a xe2x80x9ccage typexe2x80x9d winding forming a rotor is made of an aluminum wire as disclosed by JP-A-10-112949.
Furthermore, JP-A-10-274447 discloses an ammonia refrigerant refrigerator, an auxiliary fluid is used so that the electrical insulation performance may be improved and the efficiency as a refrigerator may be improved.
In the units described in the above publications, safety, corrosion or the like due to the leakage in the compressor or the compression process when using ammonia refrigerant is considered, but as an ammonia refrigerator, it is also necessary to attain downsizing, highly efficient operation, and improvement of safety, not only as a mere compressive mechanical portion but also as an entire refrigerator.
It is an object of the present invention to provide a highly efficient and compact ammonia refrigerator whose safety is further improved.
Furthermore, another object of the invention is to simplify a refrigerating cycle and decrease the amount of filling of refrigerant, and to enhance the refrigerating ability while decreasing the consumption of electric power or the like, thereby realizing energy saving.
To attain the above objects, the invention provides an ammonia refrigerator using ammonia as a refrigerant and having an ammonia refrigerating cycle in which a compressor, a condenser, an expansion valve, and an evaporator are connected through piping. The refrigerator comprises a casing which accommodates a compressor and a motor for driving the compressor and through which the refrigerant flows, a stator winding of the motor made of an aluminum wire, and a brine to be cooled by the refrigerant which is compressed in the casing and then evaporated in the evaporator.
In the ammonia refrigerating cycle, the stator winding of the motor is made of an aluminum wire, and even without a can, there is no fear of corrosion caused by ammonia, and the structure can be simplified. Also, the efficiency is not lowered. Furthermore, air conditioning, refrigerating or the like is performed through the brine cooled by the ammonia refrigerant, and therefore, safety is further improved in a portion or area to be air-conditioned and a portion or area to be refrigerated, and the amount of filling of the refrigerant can also be reduced.
In the above arrangement, it is preferable that the evaporator is a plate type heat exchanger having a plurality of plates piled, and that an inverter drive unit for controlling the capacity of the compressor is provided.
Further, the invention provides an ammonia refrigerator using ammonia as a refrigerant and having a refrigerating cycle in which a compressor, a condenser, an expansion valve, and an evaporator are connected through piping and which has brine cooled by the refrigerant, wherein the winding of a motor for driving the compressor is made of aluminum wires, the brine is cooled by the ammonia which is compressed in the compressor and then evaporated in the evaporator, during an ice heat storage operation, the brine is supplied to a heat storage tank to freeze water therein, and the cold water cooled in the heat storage tank is moved by a cold water pump.
In the ammonia refrigerating cycle, as the winding of the motor is made of aluminum wires, there is no fear of corrosion caused by ammonia, the structure can be simplified, and the efficiency is not deteriorated. Further, the brine is cooled by the ammonia refrigerant, and water is cooled by the brine and moved by a cold water pump to perform air conditioning in a room. Accordingly, the ammonia does not leak into the room, and the safety is further improved. Moreover, by performing the heat storage operation with the electric power at night, demands of the electric power are leveled, and the refrigerator is suitable for coping with the environmental problems such as ozone layer destruction, global warming, or increase of carbon dioxide.
Furthermore, the invention provides an ammonia refrigerator using ammonia as a refrigerant and having a heat source machine in which a compressor, a condenser, an expansion valve, and an evaporator are connected through piping and which has brine cooled by the refrigerant. The refrigerator comprises a compressor in which the winding of a motor is made of aluminum wires, a heat storage tank to which the brine is supplied, and a cold water pump which moves cold water cooled in the heat storage tank.
Furthermore, the invention provides an ammonia refrigerator using ammonia as a refrigerant and having a refrigerating cycle in which a compressor, a condenser, an expansion valve, and an evaporator are connected through piping and which has brine cooled by the refrigerant. The refrigerator comprises a compressor in which the winding of a motor is made of aluminum wires, a heat storage tank to which the brine is supplied, a cold water pump which moves into a room cold water cooled in the heat storage tank, a brine/water heat exchanger for performing heat exchange between the cold water which has carried out air conditioning in the room and the brine, and a three-way valve which mixes pre-cooled water cooled in the brine/water heat exchanger and cold water cooled in the heat storage tank.
The cold water cooled by the brine in the heat storage tank is moved into the room, and the cold water by which the air conditioning has been carried out in the room is cooled in the brine/water heat exchanger to be pre-cooled water. The pre-cooled water is mixed with the cold water cooled in the heat storage tank. Accordingly, the structure is simple, the cold water supplied into the room has a constant temperature, and with no surplus ability, the air conditioning can highly efficiently be performed. Consequently, the amount of filling of the refrigerant can be decreased, and the performance of refrigeration is increased while the consumption of electric power is reduced.
Furthermore, the invention provides an ammonia refrigerator using ammonia as a refrigerant and having a refrigerating cycle in which a compressor, a condenser, an expansion valve, and an evaporator are connected through piping and which has brine cooled by the refrigerant. In the refrigerator, the winding of a motor for driving a compressor is made of aluminum wires, in case of an ice heat storage operation, the brine cooled by the refrigerating cycle is supplied to a heat storage tank to make ice, in case of a cooling operation, the cold water returning from the inside of a room is pre-cooled by the brine and is divided, and one of the divided water and the other which is further cooled in the heat storage tank are mixed and moved into the room.
In the above arrangement, the evaporator preferably comprises a plate type heat exchanger having a plurality of plates piled.